Still plenoptic images are 2D images captured by specific plenoptic systems. Such systems differ from the conventional camera systems.
Plenoptic systems have been described, for example, in documents Lumsdaine et Georgiev “Full resolution lightfield rendering” tech. rep., Adobe Systems, Inc. (January 2008) and “Digital Light Field Photography”, Dissertation submitted to the department of computer science and the committee on graduate studies of Standford University in partial fulfillment of the requirements for the degree of doctor of philosophy, Ren Ng (July 2006).
In such systems, an array of micro-lenses is disposed between an image sensor and a main lens of the camera. A given number of pixels are located underneath each micro-lens. The sensor captures pixel values through the array that are related to the location and the orientation of light rays inside the main lens.
The optical arrangement of plenoptic systems makes it possible to change the refocusing plane of the 2D images after they have been captured by image processing. Changing the refocusing point makes it possible to modify the sharpness and the blur on the objects located at different depth in the 3D scene represented by the 2D image.
Advantageously, several 2D images with respective and different focalization points can be generated using refocusing from a single plenoptic image. This makes it possible to simulate different camera parameters (e.g. the camera aperture, the focusing plane, etc.). Also, the point of view can be slightly changed by image processing and the 3D depth of the scene may be recalculated.
Plenoptic systems may be cameras and also camcorders. In the latter case, a plurality of images are captured for forming a video, each image captured being a plenoptic image.
The compression (or encoding) algorithms used for compressing (or encoding) plenoptic images and plenoptic videos usually require long run times. Therefore, any improvement in term of compression run time is interesting.
Compression methods directed to light field or plenoptic images have been disclosed in documents U.S. Pat. Nos. 6,476,805, 8,103,111 and 8,155,456.
However, the methods disclosed do not fit in standard encoding algorithms used for encoding standard (non-plenoptic) images.
This may limit the development of the use of plenoptic systems although they provide advantageous features.
Thus, the inventors brought into light the fact that there is still a need for plenoptic images and/or video encoding techniques that are compatible with current (non-plenoptic) image and/or video encoding standards. In particular, there is still a need for plenoptic images and/or video encoding techniques with reduced run times.
The present invention lies within this context.